FIG. 1 depicts a prior art protection circuit 100 for protecting a load 110 from over-current stress due to a short-circuit failure 199 of a transistor 102, the protection circuit 100 comprising a current sense resistor 103 and a circuit breaker 106. The load 110 receives power from an input source of voltage 101 through the transistor 102 biased into conduction by a driver 105. In operation, when a voltage threshold is exceeded across the sense resistor 103, the circuit breaker 106 disconnects the load 110 from the input voltage source 103.
The prior art protection circuit 100 suffers high cost of components and is not well suited for integration in a monolithic die with the driver 105. In addition, circuit breaker 106 does not provide adequate protection in a system with low headroom voltage.
What is needed is an improved circuit and method for performing direct detection of the transistor failure.